I need more range on the fat bike so looking at 11-40 10 speed cassettes.
The rear mech is an SRAM XX medium cage ( currently with an 11-36 )

Will this work with a 40 tooth ?

Any help appreciated

SRAM says NO I think

Assuming that’s your mech…

Balls to what SRAM say, It will, my medium cage X9 works fine with 11-40 10 speed

SRAM does say no but I know various other mechs will work with larger cassettes beyond their claimed max.
I know the frame and hanger length will play it’s part but I’m sure others have used, are useing, or have attempted to use a medium cage with a 40t.

Any one else know if this will work?